SULPHUR AS A FACTOR THAT AFFECTS NITROGEN EFFECTIVENESS IN SPRING RAPESEED AGROTECHNICS PART III. AGRONOMIC USE EFFICIENCY OF NITROGEN
Background. In view of the increased interest in rapeseed cultivation that has been observed in Poland in recent years, and due to an increasing shortage of sulphur in Polish soils, a study was undertaken on the effect of nitrogen and sulphur fertilization on the uptake of those elements in the seeds of the spring rapeseed cultivar Star and on the agricultural effectiveness and utilization of nitrogen from fertilizers.
Material and methods. In a three-year-long study, experimental objects with different sulphur application methods (in-soil and foliar) and control with no nitrogen or sulphur fertilization were located on one field. Nitrogen fertilization at the doses of 0, 60, 120, and 180 kg N·ha-1 was the first factor, and sulphur fertilization at the doses of 0, 20, and 60 kg S·ha-1 was the second factor. The experiment was set up on degraded Phaeozems with a low sulphur content.
Results. In the conditions of joint nitrogen and sulphur fertilization, the nitrogen uptake in the seeds of spring rapeseed, as well as the agricultural effectiveness and the utilization of this element from the fertilizer were higher than without the sulphur application. In every growth season the combined use of nitrogen and 60 kg S·ha-1 usually made it possible to obtain the highest values of the studied parameters. Sulphur application method only to a low extent differentiated the uptake of the studied elements, agricultural effectiveness, and nitrogen utilization.
Conclusion. Supplementing spring rapeseed nitrogen fertilization with an application of sulphur affected nitrogen uptake and its effectiveness and utilization from fertilizers, which may have positive economic and environmental consequences.